.bigImg{position:absolute;top:50%;left:50%;transform:translate(-50%,-50%);}
@media screen and (max-width:700px){.bigImg{width:100%;max-height:100%;}}
.opacityBottom{width:100%;height:100%;position:fixed;background:rgba(0,0,0,0.8);z-index:1000;top:0;left:0}